Question

When try to connect to the mysql server through my rails application, I get the following error

D:/Program_Files/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require': 
Incorrect MySQL client library version! This gem was compiled for 6.0.0 but the client library is 5.0.27. (RuntimeError)

How can I rectify it?

Answer 1

I had the same problem as you, or at least the symptom was the same.

Background: I was using Rails 3, the mysql2 gem, and MySQL community server version 5.5.21 (32-bit) installed locally on my Windows machine. I grabbed the client library (libmysql.dll) from the MySQL installation and copied it to my ruby installation’s bin folder.

When I ran bundle exec rake db:create, I got the same error message as you and I thought “Hey, how can the client library be outdated when I got it from the latest MySQL release?”

There’s a helpful message that is shown when you gem install mysql2. Unfortunately, if you install the gem with Bundler, Bundler eats the message. Here it is:

=========================================================================
You've installed the binary version of mysql2. It was built using MySQL 
Connector/C version 6.0.2. It's recommended to use the exact same version
to avoid potential issues.

At the time of building this gem, the necessary DLL files where available
in the following download:

http://dev.mysql.com/get/Downloads/Connector-C/mysql-connector-c-noinstall-6.0.2-win32.zip/from/pick

And put lib\libmysql.dll file in your Ruby bin directory, for example
C:\Ruby\bin

Following these instructions solved the problem for me.

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